The Arctic had a winter fever: The amount of sea ice in the Bering Sea west of Alaska was less this winter than any year since written records of commercial whalers started in 1850, before the Civil War.

The part of the Bering Sea covered by ice in February was about 150,000 square miles less than average, an area nearly the size of California.

The lack of sea ice was a hardship for the people living in communities along the Bering Sea.

"Travel between communities via boat or snowmachine was difficult and limited due to thin, unstable sea ice," the report said. "At times there was not enough ice to harvest marine mammals, fish, or crabs.

A combination of unusually warm ocean water and more south winds caused the lack of sea ice.(Photo: International Arctic Research Center)

John Walsh, chief scientist with the research center, said there was clearly an element of natural variability in the form of frequent storms and strong winds, "but the magnitude of the ice loss in response to winds and air temperatures was greater than it would have been in the past, without global climate change."

Scientists at the center said the lack of ice can also affect marine mammals such as seals, walruses and whales. In addition, "the health of polar bear subpopulations are also affected by sea ice loss," said Olivia Lee, a researcher at the research center.

But overall, "the impacts of this winter’s low sea ice on marine mammal movements and timing are not yet understood," the report said.

"Communities need to prepare for more winters with low sea ice and stormy conditions," the report concluded. "Although not every winter will be like this one, there will likely be similar winters in the future. Ice formation will likely remain low if warm water temperatures in the Bering Sea continue."

The graph compares the amount of sea ice this February to the past 168
years based on information gathered from recent satellites (over the last 40 years) and historic ship logs (from shipping, whaling vessels, and the U.S. Coast Guard).(Photo: International Arctic Research Center)